In Fig.REF , left panel, the resulting radio spectrum, compared with the observed data [1]}, [2]}, is shown for four values of the thermal density inside the cavity, while the electrons spectra for the same values of the thermal density are shown in the right panel. It is interesting to see that, while the value of the thermal density does not impact too much on the shape of the radio spectrum (in fact the relative differences between different models are smaller than 10% in the whole frequency range between 100 MHz and 10 GHz), it heavily affects the spectrum of the electrons at low energies. As shown in the next Section, this fact has strong consequences on the SZE produced by these electrons.
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